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2015英语六级选词填空练习：纳米技术
Today nanotechnology (纳米技术) is still in a formative phase. Yet it is maturing rapidly. Between 1997 and 2005, investment in nanotech research and development by governments around the world ____36____from $ 432 million to about $ 4. 1 billion, and corresponding industry investment exceeded that of governments by 2005. By 2015, products incorporating nanotech will contribute approximately $1 trillion to the global economy.
Descriptions of nanotech typically characterize it purely in terms of the minute size-assemblies between the size of an atom and about 100 molecular diameters (分子直径). That____37____makes it sound as though nanotech is merely looking to use infinitely smaller parts than conventional engineering. But rearranging the atoms and molecules leads to new____ 38____ One sees a transition between the fixed behavior of individual atoms and molecules and the adjustable behavior of collectives. Thus, nanotechnology might better be viewed as the ____39____ of quantum theory (量子论) and other nano specific phenomena to fundamentally control the properties and behavior of matter.
The second stage, which began in 2005, focuses on active nanostructures that change their size, shape, conductivity or other properties during use. New drug delivery particles could release therapeutic(治疗的) molecules i...
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2015英语六级选词填空练习：社交网络
A day after the mobile phone celebrated its 40th birthday, Facebook has produced something that it hopes will make certain of the devices even more useful. On April 4th the giant social network 36 Home, new software that is designed to give it more prominence on mobile phones powered by Android, an operating system developed by Google.
This matters because more and more folk are now accessing social networks from mobile devices rather than from desktop computers and because mobile advertising 37 are growing fast, albeit from a low base. Without a robust mobile 38 , Facebook could see some of its users siphoned off by rivals born in the mobile era. And it could miss out on a 39 massive source of new revenue.
There had been 40 that Facebook was working on a phone of its own, or at least on a mobile operating system to rival Android or Apple's IOS. But dabbling in hardware at this stage of its development would be a huge risk for Facebook and developing a rival operating system would risk 41 Apple and Google, whose mobile platforms have helped power its advertising growth, eMarketer, a research firm, 41 Facebook is on track to win 11% of the $13.6 billion likely to be spent around the world on mobile ads this year.
Home, which is a group of Facebook apps, avoids both pitfalls. Among other things, it 4...
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